Over the past few decades professionally or homeowner-installed water sprinkler systems have been employed more and more in home, office and public gardens, landscaped areas and grass lawns. These systems generally employ horizontal runs or arrays of buried galvanized iron pipe of about 1.17 cm (1/2 inch) in diameter, with fixed pipe risers threaded into and extending from inverted T-unions or couplings between linear runs of the piping. The locations of the risers are dictated by the desired area to be covered by the "throw" of a sprinkler head mounted at the top of the riser. More recently sprinkler systems have been constructed and assembled using horizontal runs of polyvinyl chloride plastic pipe with vertical risers of the same plastic material adhesively bonded into the top end of inverted T-unions connecting the piping runs. Like the galvanized iron pipe embodiments, the horizontal piping risers and the inverted T-unions are normally buried a few inches under the ground surface with the risers and sprinkler heads extending vertically above the ground. While these systems are useful for many years on lawns which, due to periodic cutting, are kept at a level of from about 2- 6 cm in height above the ground level, other installations for watering shrubbery or other landscaping directly or for watering lawns from risers located in shrubbery areas, are oft times blocked from effective, even spraying by the normal growth of the shrubbery. This necessitates either periodically cutting back the height of the shrubbery, spoiling its natural top contour, or by installing a larger riser or a riser addition(s) between the existing risers and the sprinkler heads. This may necessitate digging up the ground to expose the union and separating the sprinkler head from the riser. An additional nipple or pipe length may be added and threaded between the inverted T union and the sprinkler head and/or the old and new risers joined by an additional straight vertical union. As plant growth continues more and more extensions are necessary creating more work, as well as an ugly stack of unions and nipples. In the case of plastic pipe a section of the plastic riser must be cut out in place, which is difficult in a mass of shrubbery, allowing a longer piece of plastic riser pipe or a nipple to be added and adhered on a union(s) between the original and a subsequent addition(s). Thus it can be seen that various plumbing tools, particularly including a pair of pipe wrenches or plastic pipe cutting tool(s) and adhesive applicators must be employed to raise the level of the sprinkler head so that its throw (of water) is not interfered with by adjacent growing plants.
Coupling pipes including a so-called "slip joint" have been included in various elbow-type plumbing connection between pipes having different end separations. These are exemplified in U.S. Pat. Nos. 782,552; 2,021,317 with respect to a water closet elbow connection; 1,295,106 concerning a fountain elbow; 1,799,246 for a straight pipe connection with annular tapered packing ring; 1,997,845 for a water meter coupling; 4,258,944 for a plumbing trap; 3,136,570 for a bath tub nipple sprout; and 1,613,887 for a flush tank and bowl.